Formaldehyde (for the purposes of convenience hereinafter often referred to as “FA”) is an important chemical used widely by industry to manufacture building materials and numerous household products. FA is used for example for crease-resistant finishing in the textile industry, for the production and coating of chipboards in the wood processing industry, and for the production of synthetic resins like phenolic plastics or aminoplasts in the chemical industry. Due to its high volatility FA is released into the air during the production processes and is considered as an important impact on health and environment.
FA has four basic uses: as an intermediate in the production of resins; as intermediate in the production of industrial chemicals; as a biocide; and as a component in the formulation of end-use consumer items. The manufacture of resins accounts for about 65 percent of total consumption. About one-third is used in the synthesis of high volume chemical derivatives, including pentaerythritol, hexamethylenetetramine, and butanediol. Two percent is used in textile treating and small amounts of FA are present as preservatives or bioicides in consumer and industrial products, such as cosmetics, shampoos and glues. The largest amounts of FA are used for producing condensates (i.e. resins) with urea, melamine, naphthaline sulfonate, and phenol and, to a small extent, with their derivatives. The main part of these resins is used for the production of adhesives and impregnating resins, which are employed for manufacturing particle boards, plywood, and furniture. These condensates are also employed for the production of curable molding materials; as raw materials for surface coating and as controlled-release nitrogen fertilizers. They are used as auxiliaries in the textile, leather, rubber, and cement industries. Further uses include binders for foundry sand, rockwool and glasswool mats in insulating materials, abrasive paper, and brake linings. Very small amounts of urea-FA condensates are used in the manufacture of foamed resins that have applications in the mining sector and in the insulation of buildings and transportation vehicles.
Some products based on FA contain unreacted FA in excess which may be released from the product or released through subsequent hydrolysis. One example is urea-FA resin. Urea-FA resin is a generic name that actually represents an entire class of related formulations. About 60 percent of urea-FA resin production is consumed by particleboard and plywood manufacturing, where the resin is used as glue. Urea-FA resins are also used in decorative laminates, textiles, paper, and foundry sand molds.
Finally, FA resins are used to treat textiles to impart wrinkle-resistance to clothing. Resin or chemical finishing is in most cases the last stage of modern textile production. The goal is to convert the bleached, dyed or printed fabric by mechanical and chemical treatment into suitable state for sale. One of the most important processes is the washfast finishing of woven and knitted fabrics composed of cotton, other cellulosic fibres, and their blends with synthetic fibres.
Initially, resin-finishing agents were developed to improve the shrinkage of viscose staple fabrics. These compounds were usually derived from formaldehyde and urea. In order to improve the competitiveness of cotton on the textile market, heterocyclic cross-linking reagents based on formaldehyde, urea and glyoxal have been developed and are commonly used for easy-care and wrinkle-free finishing. Due to the suspected harm in humans, FA levels in products and industrial processes have to be kept as low as possible.
The prior art discloses various technologies for the purpose of removing FA, e.g. air-borne when released from products or directly from well-known and widely used resins as introduced supra. U.S. Pat. No. 5,352,274 discloses air filtration utilizing a plurality of corrugated base sheets which are stacked or nestled and which have entrapped carbon dust for adsorption of impurities such as FA, acetaldehyde, and acrolein. This technology provides a method to adsorb FA molecules physically but not degradation by a chemical or biochemical reaction. U.S. Pat. No. 5,830,414 discloses the treatment of carbon fibers with an active small molecule such as a strong acid, strong base, or strong oxidizing agent. These chemicals can only be used to treat fibers having high chemical resistances such as activated carbon fibers. Further, fibers thus treated are potentially hazardous to handle. The use of formaldehyde degrading enzymes in air filters is described in JP2001340436.
With respect to textile industry and building materials, FA reducing agents should not adversely affect fabric properties such as hand, shrinkage, strength retention and shade or whiteness or the mechanical properties of the particleboard. And, of course, it must be economical to use in production and efficient at reasonable levels. In the textile industry, compounds having active methylene groups have been used as FA reducing agents to reduce the amount of FA released from durable press-treated fabrics as described in Textile Chemist and Colorist, Vol. 16, No. 12, p. 33, December 1984 (published by the American Association of Textile Chemists and Colorists). FA reducing agents containing active methylene hydrogens also may be added to coating compositions containing urea/formaldehyde or melamine/formaldehyde resin to reduce formaldehyde concentration (e.g. described in U.S. Pat. No. 5,795,933). Also the addition of urea and its derivatives is known to scavenge formaldehyde.
The prior art has not disclosed FA reducing agents which are effective in reducing released FA to the low levels which are currently desired without detrimental effects on the properties of the materials to be treated with said resins. Currently, the FA reducing agents most widely used in durable press finishing compositions are polyhydric alcohols, such as diethylene glycol and sorbitol and in the manufacture of particleboard nitrogen containing compounds such as urea, melamine, diazine, triazine and amine compounds (U.S. Pat. No. 4,559,097). Compounds such as these, however, are not sufficiently effective in reducing FA levels to produce the low levels which are currently desired. Moreover, they only bind FA and do not catalyze its degradation. Also some formaldehyde scavengers like urea slow down reactivity of textile cross-linkers, reducing their efficiency.
Formaldehyde Dismutase (hereinafter referred to as “FDM”) activity has been first described by Kato and co-workers in 1983 (Kato et al., 1983, Agric. Biol. Chem., 47(1), pages 39-46) but no corresponding gene has been identified until 1995 (Yanase et al. 1995, Biosci. Biotechnol. Biochem., 59(2), 197-202). The first protocol for recombinant production and purification of soluble FDM has been published in 2002 (Yanase et al. 2002, Biosci. Biotechnol. Biochem., 66(1), 85-91). A crystal structure for FDM (Hasegawa et al. 2002, Acta Crystallogr., Sect. A, 58, C102-C102) and other related enzymes are available since 2002 (Tanaka et al. 2002, Journal of Molecular Biology, 324, 519-533).